JPH03207282A - Elevator controller - Google Patents

Abstract

PURPOSE:To securely perform direct current braking with an inexpensive apparatus by installing a constant-pulse command circuit and making change-over from a microcomputer to the constant-pulse command circuit with the operation of the safety circuit of an elevator. CONSTITUTION:While an elevator is operated, a modulation command signal from a microcomputer 9 is transmitted to a PWM modulation circuit 13 through a switching circuit 11 to generate a three-phase PWM signal. The PWM signal is amplified with a base drive circuit 14 for on-off control of the arm transistors of each of the phases of an inverter 4. If the microcomputer 9 runs away, a safety circuit is operated, and a contact 10 is opened during that operation, the output of the switching circuit 11 is changed over from the output of the microcomputer 9 to the output of a constant-pulse generation circuit 12 and sent to the PWM modulation circuit 13. Thereby the output of the inverter 4 is of constant DC voltage and a direct current is passed through an induction motor 5 under DC braking while rotating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an elevator control device that applies DC braking to a car hoisting motor when an abnormal operation of an elevator is detected.

[Conventional technology]

FIG. 3 is a block diagram showing a conventional elevator control device disclosed in Japanese Utility Model Application Publication No. 62-152693. In the figure, R, S, and T are three-phase AC power supplies, (la), (
lb), (lc) are the contacts of the magnetic contactor, (2) is the converter, (3) is the smoothing capacitor, (4) is the inverter, (5) is the induction motor, and (6) is the three-phase full-wave bridge for charging. , (8) is an inverter control circuit, (9a).

(9b) is a contact point of an electromagnetic contactor.

Next, the operation will be explained. During elevator operation, an electromagnetic contactor (not shown) is energized and contacts (la).

(lb) and (lc) are closed, and the AC power supplies (R, S,
T) is converted into DC power by a converter (2). This converted DC power is smoothed by a smoothing capacitor (3) and then converted to variable voltage variable frequency AC power by an inverter (4), which is then supplied to an induction motor (5). If an abnormality occurs while the elevator is running, the electromagnetic contactor is deenergized and the contacts (Ia) and (Ib) are closed.

(IC) is released and the supply of AC power to the converter (2) is cut off. At the same time as this alternating current power cutoff, contacts (9a) and (9b) of an electromagnetic contactor (9) (not shown) are closed. Since the contacts (9a) and (9b) are applied with DC voltage converted to DC by the three-phase full-wave charging bridge (6), the DC voltage that is the contact output of the contacts (9a) and (9b) is applied to the contacts (9a) and (9b). Power is supplied to two phases of the induction motor (5) and DC braking is applied.

[Problem to be solved by the invention]

Since the conventional elevator control device is configured as described above, the rated current of the three-phase full-wave charging bridge must be increased in order to apply DC braking. Further, there were other problems such as the need for an electromagnetic contactor for switching to DC power output for DC braking.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain an elevator control device that can apply DC braking without providing a special DC power supply switching circuit.

(Means for Solving the Problems) An elevator control device according to the present invention includes an inverse converter that converts a forward converter output into a variable voltage variable frequency AC power supply and supplies power to a car hoisting motor, and a pulse width modulation circuit that outputs a pulse width modulation signal to the pulse width modulation circuit, a microcomputer that generates and outputs an output control signal of the pulse width modulation signal to the pulse width modulation circuit, and an output control signal of a constant pulse signal to the pulse width modulation circuit. It is equipped with a constant pulse generation circuit that generates and outputs It outputs DC voltage to the hoisting motor.

(Operation) According to the present invention, when an abnormal operation of the elevator is detected, the switching circuit outputs a control signal for outputting a constant pulse signal from the constant pulse generation circuit to the pulse width modulation circuit instead of a control signal from the microcomputer. The pulse width modulation circuit outputs a constant pulse signal to the inverter, and the inverter outputs DC power to the hoisting motor to apply DC braking.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (8a) is an inverter 111Jla circuit,
(9) is a microcomputer that controls the inverter (4), (10) is a relay contact that opens when the elevator safety circuit is activated, (11) is a switching circuit, (1
2) is a constant pulse generation circuit, (13) is a PWM modulation circuit,
(14) is a base drive circuit.

Normally, during operation of the elevator, a modulation command signal from the microcomputer (9) is applied to the PWM modulation circuit (13) via the switching circuit (11) to generate a three-phase PWM signal. The PWM signal is generated by the base drive circuit (1
4), and controls the arm transistors of each phase of the inverter (4) in a 0N10FF manner.

FIG. 2 is a time chart showing the operation of each part when the microcomputer (9) goes out of control while the elevator is in operation. (a) is the output of the contact of the safety circuit (not shown), (b) is the output of the contact of the main circuit, and (c) is the output of the switching circuit (10).

Now while the elevator is running, the microcomputer (9)
goes out of control, the safety circuit (not shown) operates, and the contact (10
) is opened, the output of the switching circuit (11) changes from the output of the microcomputer (9) to the constant pulse generating circuit (
12), and the PIIIM modulation circuit (1
3). At this time, the output of the switching circuit (11) becomes as shown in Figure 2 (C), so a constant PWM signal is generated in the PWM modulation circuit and the base drive circuit (14)
), and each arm transistor constituting the inverter (4) operates to control the DC power from the converter (2) to the induction motor (5). As a result, the output of the inverter (4) becomes a constant DC voltage, a DC current flows through the induction motor (5), and DC braking is applied while the induction motor is rotating. Eventually, after a predetermined period of time passes and the induction motor stops, the base signal of the inverter is cut off and the contact (la) of the main circuit contactor is cut off.

(lb) and (lc) are opened and the elevator comes to a complete stop.

〔Effect of the invention〕

As described above, according to the present invention, a constant pulse command circuit is provided, and when the elevator safety circuit operates, the PWM
The input of the modulation circuit is switched from the microcomputer to the constant pulse command circuit, the PWM modulation circuit generates a constant PWM signal for a predetermined period of time, and the inverse converter outputs a DC current to the hoisting motor. Therefore, direct current braking can be reliably applied with an inexpensive device.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an elevator control device according to an embodiment of the present invention, Fig. 2 is a time chart showing the operation of each part in Fig. 1, and Fig. 3 is a block diagram of a conventional elevator speed control device. be. In the figure, (2) is a converter, (4) is an inverter, (3) is a hoisting motor, (8a) is an inverter control circuit, (9) is a microcomputer, (10) is a safety circuit signal output contact, (11) is a switching circuit, (12) is a constant pulse generation circuit, and (13) is a PWM modulation circuit.

Claims (1)

[Claims] An elevator equipped with an inverse converter that converts the output of the forward converter into a variable voltage variable frequency AC power supply and supplies power to a car hoisting motor, and a pulse width modulation circuit that outputs a pulse width modulation signal to the inverse converter. The control device includes a microcomputer that generates and outputs an output control signal of a pulse width modulation signal to the pulse width modulation circuit, a constant pulse generation circuit that generates and outputs an output control signal of a constant pulse signal to the pulse width modulation circuit, and an elevator. a switching circuit that switches the output signal from the microcomputer to the constant pulse generation circuit when an abnormal operation is detected, and outputs a DC voltage from the inverter to the hoisting motor when an abnormal operation is detected. An elevator control device characterized by: